The primary use of this interface is to release unmanaged resources. The garbage collector automatically releases the memory allocated to a managed object when that object is no longer used. However, it is not possible to predict when garbage collection will occur. Furthermore, the garbage collector has no knowledge of unmanaged resources such as window handles, or open files and streams.

Important Note:

C++ programmers should read Destructors and Finalizers in Visual C++. In the .NET Framework version, the C++ compiler provides support for implementing deterministic disposal of resources and does not allow direct implementation of the Dispose method.

It is a version-breaking change to add the IDisposable interface to an existing class, because it changes the semantics of the class.

using System;
using System.ComponentModel;
// The following example demonstrates how to create // a resource class that implements the IDisposable interface // and the IDisposable.Dispose method. publicclass DisposeExample
{
// A base class that implements IDisposable. // By implementing IDisposable, you are announcing that // instances of this type allocate scarce resources. publicclass MyResource: IDisposable
{
// Pointer to an external unmanaged resource. private IntPtr handle;
// Other managed resource this class uses. private Component component = new Component();
// Track whether Dispose has been called. privatebool disposed = false;
// The class constructor. public MyResource(IntPtr handle)
{
this.handle = handle;
}
// Implement IDisposable. // Do not make this method virtual. // A derived class should not be able to override this method. publicvoid Dispose()
{
Dispose(true);
// This object will be cleaned up by the Dispose method. // Therefore, you should call GC.SupressFinalize to // take this object off the finalization queue // and prevent finalization code for this object // from executing a second time.
GC.SuppressFinalize(this);
}
// Dispose(bool disposing) executes in two distinct scenarios. // If disposing equals true, the method has been called directly // or indirectly by a user's code. Managed and unmanaged resources // can be disposed. // If disposing equals false, the method has been called by the // runtime from inside the finalizer and you should not reference // other objects. Only unmanaged resources can be disposed. privatevoid Dispose(bool disposing)
{
// Check to see if Dispose has already been called. if(!this.disposed)
{
// If disposing equals true, dispose all managed // and unmanaged resources. if(disposing)
{
// Dispose managed resources.
component.Dispose();
}
// Call the appropriate methods to clean up // unmanaged resources here. // If disposing is false, // only the following code is executed.
CloseHandle(handle);
handle = IntPtr.Zero;
// Note disposing has been done.
disposed = true;
}
}
// Use interop to call the method necessary // to clean up the unmanaged resource.
[System.Runtime.InteropServices.DllImport("Kernel32")]
privateexternstatic Boolean CloseHandle(IntPtr handle);
// Use C# destructor syntax for finalization code. // This destructor will run only if the Dispose method // does not get called. // It gives your base class the opportunity to finalize. // Do not provide destructors in types derived from this class.
~MyResource()
{
// Do not re-create Dispose clean-up code here. // Calling Dispose(false) is optimal in terms of // readability and maintainability.
Dispose(false);
}
}
publicstaticvoid Main()
{
// Insert code here to create // and use the MyResource object.
}
}